The fault diagnosis in multilevel converters is of great importance since they are comprised of more solid-state switches, compared with the conventional two-level converters. In this article, we propose a fast and efficient real-time fault detection and faulty component identification for an open-switch fault diagnosis based on the failure-mode algorithm for a single-phase five-level neutral-point-clamped inverter. Component modeling, complicated calculations, and load parameters are not required for realizing the proposed approach. Furthermore, the proposed strategy does not require any extra sensors. The signals already available in the control system, such as the applied switching pattern and terminal voltage, fulfill the fault diagnosis. Thanks to the proposed fault detection strategy, any misdiagnosis arising from noise existence, response time of the sensors, turn on and turn off delay times of the power switches, and measurement errors are avoided. The simulations and experiments are carried out to confirm the performance and effectiveness of the presented strategy.

A Real-Time Fault Diagnosis for Neutral-Point-Clamped Inverters Based on Failure-Mode Algorithm

Multilevel inverter topologies have been widely used in applications of wide-power range. Therefore, fault diagnosis of such circuits is becoming more and more important. The T-type topology, which is one of many multilevel topologies, has an advantage in terms of efficiency compared to the neutral-point-clamped type. This study proposes a new diagnosis method of an open-circuit (OC) fault for a three-level T-type inverter (3LT
 2
I). The proposed method is achieved by measuring the bridge voltage and its duration time. The bridge voltage includes information of switching states of 3LT
 2
I but not affected by the load. First, according to polarity of the reference voltage and corresponding phase current, working period of the 3LT
 2
I is divided into four working regions. Then, the bridge voltage is analysed in detail when an OC fault occurs in different working regions. At last, a fault diagnosis circuit is designed to achieve automatic diagnosis for the OC fault. Simulation and experimental results show that the proposed method can identify the faulty switch exactly and quickly.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-pel.2018.5377

Open-circuit fault diagnosis method for the T-type inverter based on analysis of the switched bridge voltage

This paper proposes a novel phase-shift triple full-bridge (PSTB) converter, in which all the three bridge legs are the leading legs. Thus, the switches can realize zero voltage switching over the full load range in a short time without the assistance of the series inductance. The primary-side circulating current is utilized to transfer energy from the input to the output, so that the circulating loss can be reduced significantly. Furthermore, the PSTB converter has high power density and strong robustness to open-circuit failures. Therefore, the PSTB converter would be useful for full load range and high-frequency applications. Theoretical analysis and characteristics of the PSTB converter are presented and verified on a 400-W hardware prototype. The experimental results show that the PSTB converter can achieve a peak efficiency of 90.3% when the switching frequency is 300 kHz. The power density of the PSTB converter is as high as 40 W/in3 with the help of GaN transistors and planar transformers.

A Phase-Shift Triple Full-Bridge Converter With Three Shared Leading Legs

Multiphase electrical machines are advantageous for many industrial applications that require a high power rating, smooth torque, power/torque sharing capability, and fault-tolerant capability, compared with conventional single three-phase electrical machines. Consequently, a significant number of studies of multiphase machines has been published in recent years. This paper presents an overview of the recent advances in multiphase permanent magnet synchronous machines (PMSMs) and drive control techniques, with a focus on dual-three-phase PMSMs. It includes an extensive overview of the machine topologies, as well as their modelling methods, pulse-width-modulation techniques, field-oriented control, direct torque control, model predictive control, sensorless control, and fault-tolerant control, together with the newest control strategies for suppressing current harmonics and torque ripples, as well as carrier phase shift techniques, all with worked examples.

Advances in Dual-Three-Phase Permanent Magnet Synchronous Machines and Control Techniques

http://scientiairanica.sharif.edu/article_4371_4b8e322c3c2fe290305d00812eabe62e.pdf

Fast detection of open-switch fault in cascaded H-bridge multilevel converter.

In this paper, an H-Bridge T-type converter with fault-tolerant capability under open-circuit switch failure is presented. An optimised and fault tolerant PWM control is applied to the converter, associated to a fault diagnosis block that allows detecting and localizing the open-circuit switch failure. A redundant leg with two bi-directional switches is used for fault-tolerant strategy and reconfiguration, after a fault occurrence diagnosis. Therefore, the converter can operate without performances degradation in post-fault operation. Some simulations are performed to validate the proposed fault diagnosis and the associated fault tolerant strategy.

Continuity of service of Five-Level H-Bridge T-Type Converter under open-circuit switch failure

If multi-phase machines equipped with tooth-concentrated winding with half a slot per pole and per phase offer interesting characteristics (simplified manufacturing, no space subharmonic, fault-tolerant ability), their low fundamental winding factors make their designs and controls challenging. The paper addresses the case of a seven-phase Surface-mounted Permanent Magnet (SPM) machine which has a fundamental winding factor lower than the third. This so-called bi-harmonic specificity is considered in order to achieve good torque quality (average value and ripples). Regarding the design, the magnet layer is segmented into two identical radially magnetized tiles that cover about three-quarters the pole arc. Regarding the control, the rated Maximum Torque Per Ampere (MTPA) supply strategy (h1h3 control) aims at generating a third harmonic current component greater than the fundamental. A prototype has been manufactured: the ability of the machine to provide smooth torque is experimentally confirmed through the implementation of a simple MTPA control which copes with high distortion in no-load voltage.

/pdf/design-of-a-bi-harmonic-7-phase-pm-machine-with-tooth-5farehgsyq.pdf

Design of a Bi-Harmonic 7-Phase PM Machine With Tooth-Concentrated Winding

In this paper, an open-switch fault diagnosis method for five-level H-Bridge Neutral Point Piloted (HB-NPP) or T-type converters is proposed. While fault tolerant operation is based on three steps (fault detection, fault localization and system reconfiguration), a fast fault diagnosis, including both fault detection and localization, is mandatory to make a suitable response to an open-circuit fault in one of the switches of the converter. Furthermore, fault diagnosis is necessary in embedded and safety critical applications, to prevent further damage and perform continuity of service. The method presented in this paper is based on the switches control orders and the converter output voltage level observation. In HB-NPP and T-type converters, usually some switches are ‘on’ together. Therefore, the fault localization is complicated. The proposed fault diagnosis method is capable to detect and localize in all cases an open-switch fault. Computer simulations are carried out by using Matlab Simulink and SimPowerSystem toolbox to validate the proposed diagnosis.

Open-switch fault diagnosis for five-level H-bridge neutral point piloted or T-type converters

This paper addresses the implementation of a fault-tolerant control for a seven-phase Surface-mounted PM machine (with tooth-concentrated winding to improve the fault tolerant ability). At any time, for a given torque demand, from off-line estimated electromotive force, an inherently fault-tolerant Maximum Torque Per Ampere control strategy calculates the reference currents taking into account the number of available phases. According to preliminary simulations, building the computed electromotive force with harmonics one, three and five appears as a good compromise between torque ripple reduction and peak current mitigation in safe and open-circuit fault operations. Experimental tests confirm these results.

Fault-tolerant control of a 7-Phase Surface-mounted PM Machine with tooth-concentrated winding

/pdf/an-experimental-blade-controlled-platform-for-the-design-of-1wk1ih3j.pdf

Florent Becker

Papers

Continuity of service of Five-Level H-Bridge T-Type Converter under open-circuit switch failure

Design of a Bi-Harmonic 7-Phase PM Machine With Tooth-Concentrated Winding

Open-switch fault diagnosis for five-level H-bridge neutral point piloted or T-type converters

Fault-tolerant control of a 7-Phase Surface-mounted PM Machine with tooth-concentrated winding

An experimental blade-controlled platform for the design of smart cross-flow propeller